The present invention relates to semiconductor device fabrication and integrated circuits and, more specifically, to structures for a liner replacement in an interconnect structure and methods for forming a liner replacement in an interconnect structure.
Device structures may be fabricated on a substrate by front-end-of-line (FEOL) processing and an interconnect structure fabricated by middle-of-line (MOL) processing and back-end-of-line (BEOL) processing may be used to connect the FEOL device structures. The metallization levels of an interconnect structure may include openings formed in a dielectric layer and filled with metal to form wires and contacts.
A liner may be applied to the surfaces of the openings before the primary metal is deposited. For high aspect ratio openings in advanced technologies, the liner may fail to adequately protect these surfaces during a metal deposition process that relies on a halogen-based reactant. For example, tungsten hexafluoride is a common reactant used to deposit tungsten by chemical vapor deposition. The fluorine liberated during deposition may react with the liner metal to form a metal-fluorine complex. The metal-fluorine complex is retained in the device structure and, over time, may cause damage and even result in failures.
Improved structures for a liner replacement in an interconnect structure and methods for forming a liner replacement in an interconnect structure are needed.